An amphibian is a vertebrate that is ectothermic and spends its early life in water and adult life on land. After beginning their lives in water, most amphibians spend their adulthood on land, returning to water to reproduce.
The two groups of amphibians are salamanders and toads/frogs.
They lead “double lives” Fertilized eggs develop in water. Larvae wiggle out of the egg and begin swimming. The larvae undergoes metamorphosis and eventually turns into a frog or salamander. The larva of a frog/toad is called tadpole.
The respiratory and circulatory system of adult amphibians are adapted for life on land. In addition, adult amphibians have adaptations for obtaining food and moving.
Amphibian larvae use gills to obtain oxygen from the water they live in. When they transform into an adult amphibian they lose their gills and develop lungs.
A tadpole has a heart with two chambers, like that of a fish. Adult amphibians have hearts with three chambers. The two main parts of the circulatory system are the atria and the ventricle.
Most tadpoles are herbivores. However, most adult salamanders, toads and frogs are carnivores that actively stalk and ambush their prey.
They have strong skeletons and muscular limbs adapted for moving on land. Frogs and Toads have adapted legs for leaping which requires powerful hind-leg muscles and a skeleton to absorb the shock of landing. Frogs and Toads also have adapted webbed feet to help them swim through water.
Amphibian populations are decreasing. This is due to the destruction of amphibian habitats.